1. Field of the Invention
The present invention relates to a method of decontamination for high activity nuclear polluted canisters, in particular to an interior decontamination featuring simplicity, low cost, and effectively preventing secondary spread of nuclear waste contamination.
2. Description of Related Art
After the storage canister removed from the high-activity nuclear waste storage facility, it is harmful to the workers in a subsequent nuclear facility decommissioning process due to high activity radioactive residues still remains. Therefore, it is required to comply with the ALARA regulation and consider reducing workers' exposure to environmental pollution in prior to high activity nuclear facility decommissioning operations. The decontamination operations of storage canisters shall be conducted to reduce degree of environmental pollution and the intensity of radiation to avoid air contamination and vivo pollution.
In a conventional way, the decontamination of a storage canister includes clearing contaminants adhered to the wall, the bottleneck, and the bottom of the storage canister, minimizing the radiation intensity of the storage canister and completing the collection of pollutants to reduce the volume of radioactive contamination and secondary pollution to environment. The conventional way to use dry ice as a sand material for blasting contaminants and after completion of abrading to remove contaminants off the nuclear waste storage canister for clearing, thus it can effectively reduce the generation of secondary waste pollution, however, there are many limitations of dry ice blasting technology, such as lack of hardness of the sand material made of dry ice that it became less effect when applied for the decontamination of steel storage facility. Furthermore, the dry ice blasting equipment is expensive and bulky in size, difficult for preservation and confining working area, and difficult to control air pollution. Especially, the air pollution spread problem is seemed to be unavoidable when using high-pressure air for blasting decontamination operation.
To overcome the shortcomings, the present invention tends to provide an improved method for interior decontamination for high activity polluted storage canisters to mitigate and obviate the aforementioned problems.